Interpretive Summary: There is a dirth of information from rigorous experiments available for use by organic growers or the PCAs and extension personnel that serve them. This is in spite of organic agriculture being the fastest growing sector of the agricultural economy. In working with stakeholders from the organic strawberry production industry in California we have evaluated two production practices that could potentially improve performance of strawberry in organic production fields and provide data to help growers, PCAs and extension personnel make management choices. In this study we evaluated both commercially available strawberry cultivars and mycorrhizal inoculants for their influence on yield, and mycorrhizal colonization. Cultivar choice significantly influenced yields in organic production fields. The cultivars that performed best in the organic fields differ from the most prevalent grown cultivars in the region. These findings should help growers, PCAs and extension professionals make informed cultivar selections to optimize yield. Although microbial inoculants are products that can be used by organic growers to improve plant nutrition or for disease control, none of the seven mycorrhizae products tested significantly influenced yield or colonization of the plants in this region. These results suggest that indigenous inoculum from organic farms in this region is sufficient and the application of additional inoculum may not be of added benefit. The information in this paper additionally adds to the growing literature suggesting that cultivars selected for conventional systems are not always the most appropriate for organic production systems.

Technical Abstract:
Thirteen commercial strawberry cultivars were evaluated in side-by-side comparisons in five experiments in organic strawberry production fields in central California. Seven cultivars were common to all five experiments; six additional cultivars were included in one to four of the experiments. Of the seven cultivars that were evaluated in all five experiments, the largest market yield was consistently obtained from Aromas, Seascape or Pacific. Cultivars Carlsbad and Irvine also performed well but were not evaluated in all experiments. None of the seven commercially prepared mycorrhizal inoculants that we tested resulted in an increase in mycorrhizal colonization of strawberry roots or marketable fruit yield in organic or non-fumigated fields. However, in one of six experiments, a commercial inoculant resulted in increased total yield over the nontreated control.